As a semiconductor fabricating technology and a communication technology have recently been developed, the mobile electronic device industry has expanded, and demands for environmental preservation and development of alternative energy due to resource depletion have increased, batteries have been actively studied. Batteries are classified into primary batteries that may be used only once for a predetermined period of time and secondary batteries that may be repeatedly used by being recharged. Lithium which is used as a material of a battery has advantages in that it is the lightest metal from among metals known in the nature system, has the lowest standard reduction potential, has high energy density when the battery is manufactured, and has a high voltage. Accordingly, studies of primary batteries and secondary batteries using lithium have been greatly spotlighted.
Lithium primary batteries are often used as main power supply sources of portable electronic devices or backup power supply sources. Devices to which lithium secondary batteries are applied have been diversified from small devices such as mobile phones, notebooks, and mobile displays to medium and large devices for electric vehicles and hybrid vehicles.
Accordingly, batteries are required to have high stability and cost effectiveness as well as lightweight and small design, high energy density, high charge/discharge speed, high charge/discharge efficiency, and excellent cycle characteristics.